1. Field of the Invention
This invention relates to low-concentration, high-viscosity water-based surfactant preparations containing alkyl glycosides and certain anionic surfactants, to a process for their production and to their use as detergents or cleaning preparations.
2. Statement of Related Art
It is well known that alkyl glycosides containing long-chain alkyl groups belong to the class of nonionic surfactants. It is also known, as described for example in A. M. Schwartz, J. W. Perry, Surface Active Agents, Vol. I, Interscience Publishers, 1949, page 372, that surfactant mixtures generally have synergistic effects and often show better cleaning properties than would be obtained from the sum of the values of the individual components.
Detergents containing alkyl glycosides in combination with at least one typical anionic surfactant in a ratio of 1:10 to 10:1 are described in European patent application EP 070 074. Detergents containing alkyl glycosides and anionic surfactants are also known from European patent application EP 092 877. In addition, European application EP 105 556 describes liquid detergents containing alkyl glycosides, certain other nonionic surfactants and anionic surfactants. Liquid detergents containing alkyl glycosides in combination with typical anionic surfactants are known from International patent application EO 86/02943. European patent application EP 132 043 describes a process for the production of alkyl glycosides using catalytic quantities of an anionic surfactant in its acid form. According to European patent application EP 132 046, this production process is modified by addition of certain bases after the actual reaction for the purpose of neutralizing the catalyst. The alkyl-glycoside-based intermediate products for detergents or cleaning preparations which are mentioned in these documents are aqueous solutions or pastes of relatively high concentration because the components to be mixed to form the final detergents or cleaning preparations are expected to have a high active substance content. At the same time, they are expected to be easy to handle, in other words they should have a low viscosity and should be flowable and readily pumpable. By contrast, water-based liquid products used by the consumer, including in particular liquid detergents, dishwashing detergents and universal cleaners, but also cosmetic products, for example hair shampoos or body lotions, are expected to show a certain minimum viscosity although, in general, the active substance content of such products is relatively low. Accordingly, products of the type in question normally contain thickeners which generally have the disadvantage that they themselves do not make any contribution towards the cleaning performance of the surfactant component present in the products. Typical thickeners are inorganic water-soluble salts, more particularly sodium chloride, and salts of non-surface-active aromatic sulfonic acids, for example sodium cumenesulfonate.
Organic thickeners are, typically, fatty acid alkanolamides, such as coconut oil fatty acid monoethanolamide, lauric acid monoethanolamide, oleic acid diethanolamide and coconut oil fatty acid diethanolamide, polyethylene glycol difatty acid esters and a number of water-soluble polymers.
In most cases, it is either not possible or is only possible using high concentrations to build up the required viscosity in the surfactant solution solely through the use of inorganic salts. Accordingly, organic thickeners, which are attended by a number of disadvantages, have to be used in addition to the inorganic salts. Thus, solutions thickened with polyethylene glycol fatty acid diesters often show inadequate viscosity stability in storage while water-soluble polymers are often difficult to dissolve and give rise to unwanted flow behavior.
In European patent application EP 306 843, it is proposed to use adducts of ethylene oxide and/or propylene oxide with unsaturated fatty alcohols for the purpose of thickening surfactant solutions. Although these products do not have any of the disadvantages mentioned above, there is still a need for thickeners having comparable properties for an increased thickening effect. This would make it possible to produce systems of relatively high viscosity for a given thickener content and to reduce the thickener content for a predetermined viscosity.
The problem addressed by the present invention was to provide a storable, liquid, flowable water-based alkyl glycoside preparation which, through its relatively high viscosity, would be easy to handle under in-use conditions and which would contain very small quantities of non-alkyl glycoside active substance.
This problem has been solved by a water-based mixture of certain quantities of alkyl glycoside and a certain anionic surfactant.